
    //定义画布宽高和生成点的个数
    var WIDTH = window.innerWidth, HEIGHT = window.innerHeight;
    if (WIDTH <= 375) {
    POINT = 10;
    } else if (WIDTH <= 800) {
    POINT = 15;
    } else if (WIDTH <= 1024) {
    POINT = 20;
    } else if (WIDTH <= 1400) {
    POINT = 25;
    } else {
    POINT = 35;
}

           var canvas = document.getElementById('Mycanvas');
    canvas.width = WIDTH,
        canvas.height = HEIGHT;
    var context = canvas.getContext('2d');
    context.strokeStyle = 'rgba(0,0,0,0.02)',
    context.strokeWidth = 1,
    context.fillStyle = 'rgba(0,0,0,0.05)';
    var circleArr = [];

    //线条：开始xy坐标，结束xy坐标，线条透明度
    function Line(x, y, _x, _y, o) {
    this.beginX = x,
    this.beginY = y,
    this.closeX = _x,
    this.closeY = _y,
    this.o = o;
    }

    //点：圆心xy坐标，半径，每帧移动xy的距离
    function Circle(x, y, r, moveX, moveY) {
    this.x = x,
    this.y = y,
    this.r = r,
    this.moveX = moveX,
    this.moveY = moveY;
    }

    //生成max和min之间的随机数
    function num(max, _min) {
    var min = arguments[1] || 0;
    return Math.floor(Math.random() * (max - min + 1) + min);
    }

    // 绘制原点
    function drawCricle(cxt, x, y, r, moveX, moveY) {
    var circle = new Circle(x, y, r, moveX, moveY)
    cxt.beginPath()
    cxt.arc(circle.x, circle.y, circle.r, 0, 2 * Math.PI)
    cxt.closePath()
    cxt.fill();
    return circle;
    }

    //绘制线条
    function drawLine(cxt, x, y, _x, _y, o) {
    var line = new Line(x, y, _x, _y, o)
    cxt.beginPath()
    cxt.strokeStyle = 'rgba(0,0,0,' + o + ')'
    cxt.moveTo(line.beginX, line.beginY)
    cxt.lineTo(line.closeX, line.closeY)
    cxt.closePath()
    cxt.stroke();

    }

    //初始化生成原点
    function init() {
    circleArr = [];
    for (var i = 0; i < POINT; i++) {
    circleArr.push(drawCricle(context, num(WIDTH), num(HEIGHT), num(15, 2), num(10, -10) / 40, num(10, -10) / 40));
    }
    draw();
    }

    //每帧绘制
    function draw() {
    context.clearRect(0, 0, canvas.width, canvas.height);
    for (var i = 0; i < POINT; i++) {
    drawCricle(context, circleArr[i].x, circleArr[i].y, circleArr[i].r);
    }
    for (var i = 0; i < POINT; i++) {
    for (var j = 0; j < POINT; j++) {
    if (i + j < POINT) {
    var A = Math.abs(circleArr[i + j].x - circleArr[i].x),
    B = Math.abs(circleArr[i + j].y - circleArr[i].y);
    var lineLength = Math.sqrt(A * A + B * B);
    var C = 1 / lineLength * 7 - 0.009;
    var lineOpacity = C > 0.03 ? 0.03 : C;
    if (lineOpacity > 0) {
        drawLine(context, circleArr[i].x, circleArr[i].y, circleArr[i + j].x, circleArr[i + j].y, lineOpacity);
    }
    }
    }
    }
    }

    //调用执行
    window.onload = function () {
        init();
        setInterval(function () {
        for (var i = 0; i < POINT; i++) {
        var cir = circleArr[i];
        cir.x += cir.moveX;
        cir.y += cir.moveY;
        if (cir.x > WIDTH) cir.x = 0;
        else if (cir.x < 0) cir.x = WIDTH;
        if (cir.y > HEIGHT) cir.y = 0;
        else if (cir.y < 0) cir.y = HEIGHT;

    }
        draw();
    }, 16);
    }

